/*
 * jPOS Project [http://jpos.org]
 * Copyright (C) 2000-2015 Alejandro P. Revilla
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.jpos.security;

import java.util.Arrays;


/**
 * Util class contains some useful methods.
 *
 * @author Hani S. Kirollos
 * @version $Revision$ $Date$
 */
public class Util {

	/**
	 * DES Keys use the LSB as the odd parity bit.  This method can
	 * be used enforce correct parity.
	 *
	 * @param bytes the byte array to set the odd parity on.
	 */
	public static void adjustDESParity(byte[] bytes) {
		for (int i = 0; i < bytes.length; i++) {
			int b = bytes[i];
			bytes[i] = (byte) (b & 0xfe | (b >> 1 ^ b >> 2 ^ b >> 3 ^ b >> 4 ^ b >> 5 ^ b >> 6 ^ b >> 7 ^ 0x01) & 0x01);
		}
	}

	/**
	 * DES Keys use the LSB as the odd parity bit.  This method checks
	 * whether the parity is adjusted or not
	 *
	 * @param bytes the byte[] to be checked
	 * @return true if parity is adjusted else returns false
	 */
	public static boolean isDESParityAdjusted(byte[] bytes) {
		byte[] correct = bytes.clone();
		adjustDESParity(correct);
		return Arrays.equals(bytes, correct);
	}
}



